Keeway RKV 125 (K157FMI) Tuning

**Dviine** · 04-02-2016, 07:17 PM

Hi all, first post here.

The title pretty much says it all. I'm looking to gain a little performance from my RKV 125. It uses a KW157FMI-2B engine but that's about all I know.

Here's a picture for reference
12931242_10209254251579728_2495398946394954096_n.jpg

I want to start by replacing the massive airbox with a K&N style filter and re-jetting the carb. I have started saving for an Arrow full stainless steel exhaust system.

I was thinking this filter as it has a cover to keep rain out and I believe 42mm is the correct size for the carb?

http://www.ebay.co.uk/itm/191837877710

Then what to do about the crank case breather tube and SAI tube? Are there smaller filters you can buy or should I just use some old cloth and ziptie that in place of a filter on these 2 tubes?

I'm not sure what size main jet to go for either. I was thinking 105 but I'm new to messing with engines so not sure on this size. Should I also change the pilot jet size and what will be the benefit of this? If I do change the pilot jet, what size, 40?

Will this main jet fit my carb?

http://www.ebay.co.uk/itm/271325913913?var=570217069007

I'm open to changing sprocket size also, however I don't know which way to go. I would like to have more useable power, but I also regularly top my bike out and would like a bit more top end.

Finally, what sort of performance will I be looking at after the re-jet, filter and de-cat exhaust? I top out around 65mph now, would like to get to 70mph without too much hassle.

If I'm wrong on anything, please correct me. If you want to recommend products in place of what I've posted, please link them and I'll take a look:)

Thanks guys, sorry for the long post.

**lagerlout07** · 04-03-2016, 12:22 AM

Christ where do I start lol
Yes you can get a smaller filter for the crankcase hose. Either fit it to metal stub on the crankcase or put it on the pipe. Depends on room between bottom of the carb.
Buy a blanking kit for the egr removal. A couple of quid off eBay and pull the whole system off. On top of the carb manifold just block that pipe, I cut mine short and bunged a bolt in it.

Are you planning any internal engine mods? I ask this cause I have added the uprated cam and the 150cc kit. If you do the 150cc kit you will need a bigger carb. To be honest I got better performance with the uprated cam than I did the big bore. The head ports on these Chinese bikes are too narrow so the cam in my belief was better.

If you do the air filter and exhaust you will have to up jet, I use a foam filter, I found the k&m carbs crab and abit too restrictive of air on our little engines. Foam seems perfect for them

As for front sprocket go up one tooth for abit more top end, but less pull off. You need to take a look at your cog and remove the bolt holding it on. As some have a star pattern drive shaft or like a Allen shape. Different makes use different shafts for some reason although there the same engine code. I made that mistake so save yourself a tenner there lol

**humanbeing** · 04-03-2016, 12:47 AM

Something wrong in that bike. Keeway stock = QJ157FMI-(?) as http://www.mychinamoto.com/forums/showthread.php?8079
===
Use heat-proof & "unventilated" materials (old cloth + zip tie

) block those

Don't know what's in ur bike ...
I would say measure it 1st
Keihin (slide) & clone

Jet type : http://www.jetsrus.com/a_jets_by_car..._selection.htm | (main jet) +1-2 size

**humanbeing** · 04-03-2016, 01:38 AM

Originally Posted by lagerlout07

...If you do the 150cc kit you will need a bigger carb...
...star pattern drive shaft or like a Allen shape...

Stock Keeway (QJ157....) can't use that 62mm (Suzuki / K157FMI) kit directly, otherwise as http://www.mychinamoto.com/forums/sh...ll=1#post80754
QJ157FMJ... (150) to 62 = http://www.chyangwa.net/forum.php?mo...authorid=75082
---
Vertical Suzi clone use these pattern
428
(most 125) JTF426 | (some 125) JTF410 | (150) JTF1263 | (200)JTF409

**Dviine** · 04-03-2016, 08:18 AM

Originally Posted by lagerlout07

Christ where do I start lol
Yes you can get a smaller filter for the crankcase hose. Either fit it to metal stub on the crankcase or put it on the pipe. Depends on room between bottom of the carb.
Buy a blanking kit for the egr removal. A couple of quid off eBay and pull the whole system off. On top of the carb manifold just block that pipe, I cut mine short and bunged a bolt in it.

Are you planning any internal engine mods? I ask this cause I have added the uprated cam and the 150cc kit. If you do the 150cc kit you will need a bigger carb. To be honest I got better performance with the uprated cam than I did the big bore. The head ports on these Chinese bikes are too narrow so the cam in my belief was better.

If you do the air filter and exhaust you will have to up jet, I use a foam filter, I found the k&m carbs crab and abit too restrictive of air on our little engines. Foam seems perfect for them

As for front sprocket go up one tooth for abit more top end, but less pull off. You need to take a look at your cog and remove the bolt holding it on. As some have a star pattern drive shaft or like a Allen shape. Different makes use different shafts for some reason although there the same engine code. I made that mistake so save yourself a tenner there lol

Yes, I was planning to add a big bore kit and cam but not for a month or two. So shall I just buy the bigger carb now? Will it be okay on the stock engine until I buy the 150cc kit? Is there any chance you could link me the crank filter, cam, bore kit, carb and jets you used? Sorry I just don't want to buy the wrong part. With all of this done and a 17 sprocket, what do you reckon top speed (roughly) would be and will I see a significant increase in acceleration? Thanks. You're a massive help!

& humanbeing, are you trying to say I have the QJ157FMI, not the K157FMI, because my engine definitely has the K number on it